Sure, you thought it had already happened – but not officially. Tablets will almost outship all other types of PCs combined next year, forming nearly half of the total market (desktops, notebooks and tablets).

The worldwide PC market grew 18 percent last quarter, despite the fact that desktop and notebook shipments continue to decline. Tablet shipments accounted for 40 percent of PC shipments in Q3 2013, less than a half-million units behind notebooks. Tablet domination is set to continue, Canalys predicts. The analyst firm expects 285 million units to ship in 2014, growing to 396 million in 2017.

Apple and Samsung are expected keep ahead of their competitors for a while, but there could be challenges for both vendors as competition in the tablet market continues to heat up.

Canalys says the launch of the iPad Air and new iPad mini will strengthen Apple's lead position in the fourth quarter. The Silicon Valley giant's desktop and notebook business has remained stable while other vendors have seen their shipments deteriorate. But protecting high margins in its PC sector won't help going forward.

“Apple’s decline in PC market share is unavoidable when considering its business model. Samsung narrowly took the lead in EMEA this quarter and Apple will lose its position to competitors in more markets in the future," said Canalys senior analyst Tim Coulling. “However, Apple is one of the few companies making money from the tablet boom. Premium products attract high value consumers; for Apple, remaining highly profitable and driving revenue from its entire ecosystem is of greater importance than market share statistics."

Microsoft will make a bit of a push in tablets next year, Canalys forecasts. The software giant will nab 5 percent tablet share, up from just 2 percent in 2012.

Android operating systems will be responsible for driving growth in the market and are forecast to take 65 percent share in 2014, with 185 million units. Samsung continues to lead with strong year-over-year growth coming from its broad tablet portfolio. In the third quarter, the Korean giant has a 27 percent share of Android tablet shipments. But with hundreds of small-to-micro brand vendors in established and high-growth markets, as well as international players, Canalys says this market-share stat will also start to decline.